Salus
by Kanoi-chan
Summary: Dean is a demon now, and that leads to some very particular urges. Some he handles with finesse, others? They stump him, leaving him an angry, raging mess of himself. Thankfully, a very fallen Castiel is there to pick him up when the need arises. And if sometimes Dean is the one doing the picking up, well than that's just a bonus for both.
1. Caries

AAAHHHH! What am I doing with my life! Anyway! This had been floating around ambiguously in my head for... a month? Maybe. But I just couldn't figure out how to write it. Then the song "Come With Me Now" by The Kongos inspired the atmosphere/feel, but I still couldn't make that connection. It all finally came together on the way to work one day when "Maps" by Maroon 5 came on. First, I was like "huh... this is SO Destiel!" Then it hit me, and I finally had the characterization in down in my head.

Title is Latin for "Safety," which is what the theme of this fic is kind of about. The title for this particular chapter is "Caries," which is Latin for "Corruption." ...This is all because I have a terrible obsession with making titles from Latin words (like I know Latin or something... lol), ESPECIALLY when it comes to my Destiel.

Disclaimer: I do not own Supernatural. Apparently, if I did, all the episode titles would be in Latin?

* * *

Sam actually winced at the cracking sound, and if the werewolf hadn't been such a fucking dick, he probably would have felt bad for the guy. As things stood, though, Sam was perfectly fine with standing back as Dean beat the shit out of the monster, bones snapping as they came into contact with Dean's fists.

After Dean had become a demon and started hunting again, Sam had, at first, struggled with the inhumanity of his brother's actions. He'd since learned it was best to let Dean take out his need to inflict pain and suffering this way. Dean was at least doing a little good this way, and it was better than what happened when they tried to keep him on a tight leash.

One final crack echoed throughout the warehouse as Dean snapped the monster's neck. Utter silence followed. Dean dropped the now-limp body, watching, eyes completely black, how it crumbled to the floor. Sam's stomach churned anxiously, and the thickness of the silence was starting to get to him.

Sam cleared his throat. "Right. Well, since you're done, we should get back to the bunker."

Dean rounded on him, black eyes narrowing dangerously. "What makes you think we're done?" he asked, voice laced with dark intent.

"Um... because you killed the werewolf," Sam answered, not in the least bit threatened by his brother's display. Dean had been a demon for months now- if he had any intentions of harming Sam, he would have done it by now.

Dean's lip twisted hideously into something between a sneer and a smirk.

"Come on, Sammy," he crooned, "since when were you so unimaginative?"

Sam actually rolled his eyes, letting out an exasperated sigh. "Come on, Dean. Cas is-"

Before he could even say what Cas was doing, Dean cut him off with an inhumane howl of anger.

"Fuck Cas!" the demon growled.

Sam simply raised an eyebrow at his brother.

Dean glared at him, all but growling through labored breaths. And then, suddenly, as if he hadn't been having some kind of freak out, Dean stood up straight, his breath evening out, and eyes flashing back to green.

Sam raised the other eyebrow, looking thoroughly bemused.

Dean sent a devilish smirk his brother's way. "Well, Sammy, you may have had enough fun for the evening, but I'm just getting started."

And with a showy flash of sulfur and smoke, he was gone.

Castiel glanced up from his book when he heard someone enter the bunker. When he saw Sam walk in, fingers pinched around the bridge of his nose, Cas tilted his head to the side, watching as the hunter made his way down to the main level.

"You're alone," he observed.

Sam glanced up, as though he had just noticed the angel (which was entirely possible, the younger Winchester having seemed very immersed in his own thoughts).

"Hey, Cas," Sam greeted, flopping down into a chair. He pinched the bridge of his nose once more, sighing in frustration, before sprawling out across the seat and staring up at the ceiling.

Castiel continued to stare at the Winchester patiently.

Several minutes passed this way, until Sam finally looked up at the other man, wearing a tired smile.

"You've got to know how creepy that is," he said lightheartedly, referring, of course, to the angel's continued staring.

Castiel continued to watch him, replying, "Your brother has tried to explain it to me at great length."

This earned a chuckle from the hunter.

Sam met Castiel's eyes, and the small smile fell off his face. "He's getting worse, Cas."

Castiel broke the eye contact, making a small sound of acknowledgment. His eyes went back down to the book in his lap, studying it as though it held all the answers he sought.

Sam let his head fall back again, running his hands over his face and then through his hair. "I don't know what to do, Cas."

Castiel hummed in thought, still staring at the book.

When Dean finally returned to his room at the bunker, it was early morning, the sky just beginning to turn gray, and he was drunk off bloodshed and actual alcohol both. It was an ambrosia of debauchery that helped ease and distract from the other demonic desires and fixations that made to tear apart his mind. However, when he found Castiel in his room, the pleasant buzz was quickly doused out.

The damn angel was sitting on his bed, staring at him expectantly with those fucking endless blue eyes. He noticed the dark circles under Cas's eyes- the bastard had been waiting up for him.

Dean's stomach burned pleasantly at the thought of pushing the angel into the mattress and making his wait so very worth his while.

These were exactly the thoughts he'd been running from lately, and yet here Cas sat on the demon's bed, all disheveled and ripe for the taking.

"Dean," Castiel greeted, a hint of disapproval in his voice, and said demon found himself distracted by the angel's lips- oh, the things he could have those lips doing...

Utterly disgusted with himself for the train of thought, Dean's lip curled up in an ugly snarl as he growled out, "What?"

A look of hurt flickered across Castiel's face, but it was gone as quickly as it had come. Still, it was enough to pierce something deep within Dean, enough to make guilt churn in his stomach alongside the dark desires directed at his friend.

Castiel regarded Dean coolly. "Sam and I are worried about you."

Dean let out a harsh bark of laughter, causing Cas to knit his brow and adorably tilt his head in confusion.

Dean grinned wolfishly at him, advancing on him. "You should be more worried about other things. Yourself, for example."

He reached a hand out and wrapped it around the angel's throat. It was supposed to be a scare tactic, Dean not really wanting to harm the angel, but when his fingers met Cas's flesh, a white, hot spark ignited in him. He swallowed thickly, jaw clenched and fingers twitching with the need to add pressure to the touch. Meanwhile, Cas just kept staring up into Dean's now black eyes, unmoving and unafraid. It was too damn much.

Dean ripped his hand away with a bestial howl so loud that it reverberated against the concrete walls. He wouldn't be surprised if Sam had heard and ran down to check it out (good, let him remove the infuriatingly stubborn angel).

He fisted both hands into his hair, breathing heavy and rough, turning his back to Cas. He could still feel those eyes, though, boring into his back, and it sent his blood boiling.

Faster than human eyes could comprehend, Dean surged at the angel, pinning him to the bed. Dean flexed his fingers experimentally around Castiel's neck.

"I could ruin you," he threatened, staring deep into blue eyes. Blue eyes that held no fear.

"You won't hurt me," Castiel insisted assuredly.

"Don't be so sure about that," Dean snarled in Cas's face, fingers tightening around his neck, hand pressing closer against the oh-so-fallen angel's delicate windpipe.

Still, Castiel's confident gaze never faltered, and it sent a white hot rage through the demon.

"Don't say I didn't warn you," he growled, mere centimeters from Cas's face. And something in him snapped.

Tangling his free hand into Cas's hair, pulling hard, he crashed his lips to the ones below him. It was all teeth and carnal hunger- a need to dominate and ruin. Cas was unresponsive below him, causing him a feeling of bitter victory at his rightness. It was a feeling that was short lived.

Castiel's hands found their way into Dean's hair, kissing the demon back. The bastard even had the gall to **moan**.

It took Dean by surprise, but more than that, it settled the burning rage in his body more than anything else had to date.

* * *

Huge thanks to my beta, PharoComics! I may not have taken a lot of her direction this time around, but it's always so appreciated, and she saved me from some very embarrassing typographical blunders.

So! First of all, I hope Sam was up to par! This was the very first time I've ever written him, and it was simultaneously easier than expected while also being much more difficult than anticipated. Like... his "bitch" voice? So easy. Other parts? Not so much lol.

Also, this will be AT LEAST three parts. That's how I have it mapped out in my head, anyway, but as I say that, it's starting to spin off on it's own, so... Maybe more? But definitely no less than three. Though don't ask me when the next part will come out. Your guess is as good as mine lol.


	2. Egeo

I promise I didn't forget about this fic! Life has just been incredibly hectic, but I **finally** have part two out for you guys. This... Is pretty much pure, unrepentant smut, so... Also, on that note, this is my first attempt at writing smut as explicit as this, so... hopefully it's good. Be gentle?

This chapter's title "Egeo" is Latin for "to need."

Also, thank you to PharoComics for betaing!

* * *

Castiel was a grounding force by this point, something he couldn't do without. He helped keep the demonic rage from spilling over, and honestly? Dean was starting to think that was all that kept him grounded in the last vestiges of his humanity. The demon in him roiled at any other attempts to be tamed, even when it was Dean himself that was quashing those urges because he knew that doing otherwise would leave Cas upset and disappointed in him (he figured he should feel bad Sam didn't factor in somewhere, but the fact was that he didn't, and Dean could no longer care about that).

All of this was why hunting trips with his brother sucked by this point. Before he'd discovered relief in the form of Castiel, the violence had been therapeutic in its own right, even if it had left his mutilated soul disquieted. Now, however, it only seemed to agitate him further, egging on the ever growing violent streak in him. After the first few disastrous hunts post-Cas-therapy, he and Sam had had to work out a system of sorts, especially for the hunts that were farther away from the bunker. Dean would drive them out to wherever it was they were headed, still loving the purr of his baby under him, but the keys were all Sam's on the way back. Actually, Sam had the whole car on his way back home, as Dean more often than not popped himself back to the bunker and his fallen angel. Which is how they now found themselves in a gloriously empty stronghold for about three days, and thank whoever demons send their praise to for that, because Dean was particularly wound up after this most recent hunt- a couple of ego-maniac shifters that refused to go down without a brutal fight.

It was how he found himself pushing Cas further into the soft give of his mattress, smirking against the angel's lips as Cas moaned at the manhandling and rub of Dean's clothed cock against his own.

"Missed you, Cas, needed you," he found himself murmuring as he peppered kisses and nips along Castiel's jaw, enjoying the rough prickle of stubble against his lips.

"Rough-" Cas choked on a pleasure groan as Dean unforgivingly ground their hips together- "Rough hunt?"

Dean gave a cheshire grin, teeth clamped around Cas's ear lobe, slowly dragging down, earning him a delightful little whimper in return. "Shit yeah. Damn shifter bitches. Hate them."

He almost started seeing red again at the memory until Cas's sharp call of "Dean!" pulled him back to the present. He loosened his bruising grip on the other man's wrists, pressing an apologetic kiss to the corner of Castiel's mouth.

"Sorry." And he meant it, a small flicker of rare guilt flitting about in his stomach.

He could feel Cas's mouth twitch up into a small smile under his lips. "It's fine," he promised. Which was good because Dean wasn't sure if he could stop by this point. He'd needed this, Cas's solid body under him, to remind him to just keep it all together, to not go off the deep end and onto some demonic torture spree.

And once again, he was lost in his own head until Cas lifted his hips up to rub his erection against Dean's lewdly. "Stay with me," he commanded, and Dean was more than happy to oblige.

Fisting a hand in Cas's dark hair, Dean pulled the angel in for a bruising kiss, just wanting to drown, drown, drown in it until the fire in his soul stopped burning. Cas's now free hand on the back of his head kept him grounded and in the moment. Clothing quickly became too restrictive, too much a reminder that there was anything other than the two of them in the world, and as such was dealt with swiftly.

And Dean could admire this view for the rest of his life- Cas's head arched back against the pillows, short of breath with a flush starting at his chest and traveling upwards, his hands tangled in Dean's hair as he sucked marks into the soft skin of the angel's inner thigh. And Cas watched him the whole time, blue eyes half-lidded and smoldering as if he had every bit of grace left in him and intact. Dean could get drunk off that image better than the aged scotch Crowley loved to ply him with.

He slowly dragged his teeth against the skin of Cas's ball sac, and just like that a whole new image played out for him- Cas's head completely thrown back, a gasp of pleasure choking off into a sound that words couldn't describe. It left Dean feeling empowered and bold, sliding his tongue up and along the vein on the underside of Castiel's cock. He received needy little whimpers and fingers flexing against his scalp in return. He tongued the slit, tasting the salt and sweetness there that could only be ascribed to Cas, before slowly engulfing the head, cheeks hollowing out. Cas's cry of "Dean, fuck!" rang out in the room.

He slowly worked the other man's shaft, swallowing deeper and deeper each time he descended back down, until his nose was buried in the dark curls at the base and everything around him became centered completely on Cas- his smell, his taste, his moans and pleas. And then Dean hummed around his dick, and the angel was undone, crying out wordlessly as he spilled down Dean's throat, the demon milking him for all he was worth.

Dean barely had time to savor the taste on his tongue before Cas was yanking him up by his hair and into a breathtaking, utterly needy kiss. When he pulled back, he was met with hooded eyes and a lazy, contented smile. If Dean wasn't already rock hard, the sight of his angel being so debauched would certainly cause it. Cas's lazy smile morphed into something closer to a lazy, come hither smirk.

"Your turn," he hummed out.

Dean smile-smirked back before nuzzling under Cas's jaw. "Roll over."

He sat back and watched as Cas got onto shaky arms and legs, presenting himself to Dean. The demon's eyes flashed black at the sight of Cas's pink hole that he planned to very soon be filling up, and his cock gave an appreciative twitch at the image.

"Look at you," he purred, chest sliding up along his angel's back, "all blissed out and ready for me. Gonna fuck you good. Know you want it."

Cas responded with a whimper, canting his hips back towards Dean.

Dean chuckled. "You do want it, don't you?"

"Yes. Please, Dean. Yes." Cas was gasping now, having managed to slot Dean's dick between his cheeks and rutting against it.

With a growl, Dean gripped Cas's hips hard enough to bruise, stilling the motion. "Be patient, Cas. You're getting ahead of yourself."

Castiel let out a displeased groan, burying his face into the pillows and bunching the fabric of the pillow cases in his fists. Dean chuckled, kissing his way down Cas's spine, all the way down to the curve of his ass. With one last glance up at Cas's head still buried in the pillows, he slid his tongue down the cleft to circle his hole teasingly. The response was immediate, the angel gasping and making to arch into the action, but when he found his hips still held in place, he mewled helplessly.

"Dean. Please."

Dean chuckled at the whine, the vibration going straight to Cas's over-sensitive nerve endings and causing him to cry out and scrabble for purchase in the pillows. Dean just continued flicking his tongue across and around Cas's fluttering hole, occasionally dipping his tongue in, causing Cas buck extra hard against Dean's hands.

"You like that, Baby?" Dean asked with a chuckle and a nip to his ass.

"Yes, Dean. Yes. Fuck me, Dean. Please just fuck me." Cas was breathless, voice already wrecked, and if Dean was a being of lesser fortitude, he was sure he'd be doing just as the angel asked at that very moment.

"Don't want to hurt you, Cas," he reasoned, voice playful, as he pressed a kiss to the spot he'd just bitten.

"Won't hurt. Just need you."

Dean stilled for a moment, Cas's words getting to him, before slowly moving his hands from Cas's hips to cup and massage the globes of his ass. When he sat up, he could already see bruises forming from where he'd been gripping the fallen angel's hips. It sent something primal roiling through his gut, and he was suddenly all too aware of his own erection laying heavy against his hip, all too aware of the demon itching at his insides.

"Need you too." When he said it, his voice was raw with emotion. Castiel glanced back at him, offering a small reassuring smile. Dean tried to smile back, but it was strained with the sudden need to be inside Cas, to feel nothing but the angel clenching around him.

Dean quickly found the lube and prepped Cas, the angel already loosening up and relaxed from Dean's ministrations with his tongue. And then he was slicked up himself, slowly seating himself in Cas's tight hole. It was tortuously slow between the burning need and Cas's pleas to keep going despite the last bit of resistance from his body, and when Dean was fully sheathed, he let out an animalistic growl, latching his teeth onto the back of Cas's neck. Castiel cried out, shoulders arching into the bite, and Dean set a grueling pace, pistoning his hip in and out, the slap of skin on skin filling the room. He could taste Cas's blood on his tongue as he kept his teeth clamped in place, the sweet tang of fading grace clearing his mind of all but the beautiful body below him.

Castiel was screaming, voice wrecked beyond recognition, as Dean angled just right to hit his prostate every time, a litany of "Dean" and "please" and "harder" rolling off his tongue better than any porn star Dean had ever seen, and it was moments like this that left Dean wondering at how right they fit together in every way and what an idiot he'd been as a human for missing out on this.

"Dean- Dean, I need..." Cas couldn't quite get out what it was he needed, didn't need to anyway. Dean finally freed Cas's skin from his teeth, hauling them both up to their knees. Castiel turned his head and Dean met his lips in a sloppy kiss, tongues tangling around moans and each other.

Castiel was all but sobbing as the new angle brutalized his prostate further, and when Dean reached down to wrap his hands around his cock, he barely got one stroke in before Cas shattered, coming violently with a scream of Dean's name tumbling from his lips.

Dean buried his face against Cas's shoulder, panting violently, still chasing his own release. It only took about a minute more until Dean was unraveling, himself, with a cry of "Jesus, fuck, Cas!" and burying himself into the angel as deeply as possible.

They both tumbled to the bed, utterly spent, and once Dean caught his breath, he marveled at the spectacular bite mark he'd left on Cas's neck. And then he winced, because Cas wasn't at full strength anymore, and that wouldn't heal quickly or prettily. But Cas's breathing had already evened out in the way it did when he slept, so Dean just placed a chaste kiss to the ugly mark. He nuzzled at the space between Castiel's shoulders, pulling the angel flush against him, settling in to rest himself until Cas woke up, thoughts of shifters and hunts and all things demonic rage far from his mind.

This, Cas, here in his arms, was just what he needed.


	3. Pacisci

The title of this chapter means "to bargain."

* * *

There was no hunt this time. There were no monsters to fuel Dean's rage. There was only a frail, failing form in his bed, and each cough that emanated wracked his body as if it were his own.

He'd returned from a hunt a week ago, needing the soothing reminder that was Cas's body under his fingers, pliable to his urges. He'd needed the reminder that there could be a Heaven for him on Earth despite the damnation of his soul. He'd returned to the bunker ahead of Sam in a flurry of sulfur and smoke, storming off to his room, where he knew Cas would be waiting for him. Only that he wasn't. The room was immaculate, unlived in. Dean called out, but there was no answer. Irritation crept in to intermingle with the rage. He made his way to the kitchen, barely containing that sea of red burning behind his eyes, thinking that perhaps Cas was there. After all, he had to eat now-a-days. No such luck. Biting back a growl, he teleported to the library, another one of the fallen angel's frequent haunts. He searched the spacious room from front to back, top to bottom, but had no luck in finding his lover there either, and with each row of books that did not contain a head of dark hair, his rage slowly morphed to mounting panic. He quickly searched several more rooms, working himself into a tizzy, before finally coming to the room Cas had used before permanently moving into Dean's.

Relief sagged into his bones in the moment he saw the rumpled sheets on the bed. He wasn't sure just what had made Cas return to this room, but at least he had some proof his angel was safe. Except that Cas wasn't actually around, and the adjoining bathroom was eerily silent. Panic clutched once more at his windpipe as he wrenched open the door, half expecting Cas to be on the other side taking a shit, ready to pounce into a lecture on how, as a human, he needed privacy.

Castiel was, in fact, on the other side of the door. Only he was by no means ready to lecture anyone. It took Dean an inordinately long amount of time to actually place the crumpled body on the cold tile floor as that of his lover. He stared on, shell-shocked, as cold dread settled into the pit of his stomach. He learned in that moment that demons don't feel the urge to vomit in the way that humans do, because surely if he was still mortal he'd be on the floor shaking, throwing up all his cookies, as it were. Instead, he slowly made his way toward the angel, no, the man, and kneeled down next to him. With only-slightly-trembling hands, he rolled Cas onto his back, momentarily relieved to find that he was still warm, only to then realize that the problem was that he was altogether too warm, fever flushed and clothes soaked through with sweat.

He gently shook the smaller man, hoping he wasn't quite so bad as to be in a fever-induced coma. "Come on, Cas, you gotta open those baby blues now. Can't be sleeping on the floor." His voice sounded foreign- soft and calm in ways he knew he couldn't be feeling.

He listened to his own heart beat no more than four times before Cas groaned weakly, so close to a whimper that even Dean felt the pain.

Castiel squinted up at him and opened his mouth to speak, for only a rasping cough to pass his lips. Dean smiled weakly, brushing a sweat-soaked lock of hair off Cas's forehead.

"Let's get you to bed," Dean whispered, lifting Cas up into his arms as a young groom would his bride, as though he weighed nothing at all.

Cas buried his face into the crook of Dean's neck, and the demon could feel every shiver that quaked through the man's body. He couldn't help kissing the crown of damp, dark hair before placing Castiel in the bed and tucking him in.

"I'll be right back," he promised, ready to teleport to the kitchen, but then thought better of it, not wanting the smoke and sulfur left behind to aggravate Castiel's cough further, so he took the slower way. He fetched a glass of water, bringing it back to the fallen angel, who seemed to be wavering in and out of consciousness.

Sitting on the edge on the bed, he helped Cas up into a sitting position, bringing the glass to Cas's lips. "Come on, need you to drink a little for me." And bless Castiel, he did, gulping down the water like a man lost in the desert. "Hey, hey, slow down, buddy. Don't want you to choke." Castiel followed the command, drinking slower, until the glass was empty. Dean smiled at him, kissing his forehead. "Good job. You just rest here for a minute while I get a bath ready for you. Gotta get you out of those wet clothes."

Dean drew a warm bath and helped Cas out of his clothes and into the tub, Castiel trembling the whole time from exhaustion and fever chills. Then Dean quickly stripped out of his own clothes, climbing into the too small tub behind Cas. He helped him wash himself and massaged the knots out of Cas's neck and shoulders. Before the water could get cold enough for Cas to start shaking again, Dean got out of the tub, quickly drying himself off, and then helped Cas out, toweling him off and helping him get dressed into clean, dry sleep clothes. He tucked Cas back in, and then crawled into the bed and curled around the fallen angel.

That had been a week ago. When Sam had finally made it back to the bunker the following day, Dean told him what had happened, trying to keep a lid on his fears. They'd both agreed that Cas must have just caught a cold or the flu, but it didn't seem that any amount of chicken soup and tea with honey could abate the illness. Eventually, they had to accept that this was no mild-mannered virus, and was instead Castiel's stolen grace finally burning out. This was the end.

Only that Dean couldn't accept an end. He needed Cas, always had needed Cas, but it was so much more now. There was a symbiosis between them, the one giving the other meaning and reason to live, and Dean wasn't about to let that flicker out, not when he'd just grown accustomed to it. There was no point in existence if there was no Castiel by his side, no point in anything existing, and while he was sure that was a very demon way to think- ready to ravage the whole of all planes of existence if he no longer had pretty blue and fallen eyes to look into- but he was also sure he didn't care one way or the other what kind of way it was to think. All that it mattered was that it was his truth; that he refused to exist without his angel, fallen or otherwise.

And he was ready to grease whatever palms, sew whatever deals, were necessary in order to ensure that he never had to.

He was no crossroads demon, but he'd always known how to get what he wanted.

* * *

And that, my friends, is the end. It didn't turn out exactly as I had initially planned, but I'm decently pleased with it. Also, believe it or not, I came up with this particular plot MONTHS before the season 10 premier. This had pretty much been my plan all along since the inception of this story. I feel psychic lol. Anyway, I hope you enjoyed this little journey with me. If you liked this, be sure to check out my other SPN fics. Though they're all AU, except a few of my one shots.

Anyway! Thank you to Pharocomics for going on this journey with me and being an awesome beta the whole way through.


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